Project Summary/Abstract About 3 million people in the US are living with hepatitis C virus infection (HCV), and the burden of HCV is highly concentrated in incarcerated populations. Curative HCV treatment is available, but infrequently available in corrections settings. There are disparities in access to HCV care between White and Non-White people in the community, and non-White people have higher rates of incarceration. As a result, liver disease is one of the leading causes of death in inmates, especially Non-White inmates. One feasible approach to overcoming health disparities for HCV care in incarcerated populations is increasing the diagnosis of HCV. This approach is particularly pragmatic for the jailed population?people incarcerated for less than 2.5 years?with linkage to HCV treatment arranged post-release. Opt-out infectious disease testing both increases overall frequency of testing and decreases racial disparities in testing. Unlike opt-in testing, which requires explicit agreement to perform testing, opt-out testing informs individuals that they will be tested unless they decline. Opt-out HCV testing in prisons is recommended by federal policy, and recently mandated in all Massachusetts (MA) prisons through a court ruling. Opt-out testing is not mandated in MA jails. The overarching goal of my research proposal is improving access to HCV testing in jails with the ultimate aim of reducing the prevalence of HCV in the US. The first aim of this research proposal is a comparison of current HCV testing practices to testing policy through retrospective chart review with a focus on racial disparities in access to testing. The second aim is a hybrid effectiveness-implementation aim with the goal of implementing opt-out HCV testing and evaluating effectiveness of opt-out testing to increase testing frequency and decrease racial disparities in HCV testing. Imbedded in the research activities is a robust training plan including advanced epidemiology and implementation science methodology. Support of key stakeholders has been confirmed, including representatives from the criminal justice system, health care providers in the jail, and the MA public health department. Augmented by training in innovative and synergistic methodologic disciplines, completion of this research proposal will be the foundation for a successful research career devoted to using implementation science methodology to improve the quality and equity of health care provided in corrections settings.